10105 1ST DR SE 2021-12-14 - Laserfiche WebLink

GUIDE TO DEVELOPING A SOIL MANAGEMENT PLAN This section outlines steps for professional specifiers to prepare a Soil Management Plan (SMP) to meet the provisions of BMP T5.13 in the Department of Ecology's Stormwater Manual for Western Washington. The main steps to creating the SMP are: Step 1: Review Site Landscape Plans and Grading Plans. Examine all areas that will not be covered by structures, impervious surfaces, or stormwater detention / infiltration structures, to assess how grading will impact soil conditions and determine areas where different soil treatments may be applied. Those allowed soil treatment options are: Option 1: Areas where native soil and/or vegetation will be retained in place; Option 2: Areas where topsoil or subsoil will be amended in place; Option 3: Areas where topsoil will be stripped and stockpiled prior to grading for reapplication, and; Option 4: Areas where imported topsoil will be applied. Step 2: Visit Site to Determine Soil Conditions Working with plans, check the soil in each area to identify information outlined in the chart below. Identify compaction of subgrade in each area by digging down to a level that will be 12" below finished grade. Use a shovel or "rod penetrometer" driven solely by the your weight, as described in Section 3, and illustrated in Section 6 "Field Guide to Verifying Soil Quality and Depth." Areas Assess Conditions Include Information on SMP Native vegetation / ✓ Established native plants. ✓ Identify those areas to be left undisturbed and fenced undisturbed soil to be ✓ Undisturbed topsoil and duff layer. during construction. preserved Topsoil not requiring ✓ Depth of compacted layers less than 12 ✓ Will scarification be needed? What depth of scarification grading, but cleared of inches deep. is required to allow compost incorporation and achieve native vegetation ✓ Presence of organic matter that may make 12 inches uncompacted depth? amendment unnecessary, or allow ✓ Will area be amended with compost or topsoil at "pre - calculation of reduced amendment rate. approved" rate, or custom calculated rate? ✓ If planning to use calculated amendment ✓ Can areas be protected from compaction during rate, sample and test soil as described in construction? Step 4. Areas to be cut during ✓ Quantity of topsoil that can pbe stockpiled ✓ Will scarification be needed? What depth of scarification grading and reapplied. is required to allow compost incorporation and achieve ✓ Depth of any compacted layer less than 12 12 inches uncompacted depth? inches below ultimate finished grade. ✓ Will topsoil be stockpiled during grading and reapplied? ✓ Presence of organic matter in subgrade or Will it require supplemental topsoil or compost to achieve topsoil that may make amendment 8 inches depth at specified organic content? unnecessary, or allow calculation of reduced ✓ Will area be amended with compost or topsoil at "pre - amendment rate. approved" rate, or at custom calculated rate? ✓ If planning to use calculated amendment rate, sample and test soil as described in Step 4. Areas to be filled during ✓ Estimate what subgrade conditions will be ✓ What depth of scarification is required to allow compost grading when fill is in place. incorporation and achieve 12 inches uncompacted depth? ✓ Depth of any compacted layer less than 12 ✓ Will area be amended with compost or topsoil at "pre - inches below ultimate finished grade. approved" rate, or custom calculated rate? ✓ Presence of organic matter in fill soil that may make amendment unnecessary, or allow calculation of reduced amendment rate. ✓ If planning to use calculated amendment rate, sample and test soil as described in Step 4. 10